Apparatus for regulating high voltage



March 20, 1951 Filed Feb. ll, 1949 K. G. MORRISON 2,546,106

APPARATUS FOR REGULATING HIGH VOLTAGE I5 Sheets-Sheet 1 IN VENToR. KEN/v5 TH 6. MMR/50N ATTORNEY.

March 20, 1951 K. G. MORRISON APPARATUS FOR REGULATING HIGH VOLTAGE 3 Sheets-Sheet 2 Filed Feb. ll, 1949 mmv NYE March 20, 1951 K Q MQRR|SON 2,546,106

APPARATUS FOR REGULATING HIGH VOLTAGE Filed Feb. 11, 1949 3 Sheets-Sheet 5 Q I I 6 7- QD I I .2//

- 3l gg N i I NV E N TOR KENNETH 6Y MoRR/.so/v

ATTRNEY.

Patented Mar. 20, 1951 APPARATUS Fort REGULATING HI'GH VOLTAGE Kenneth G. Morrison, Oakland, Calif., assigner/to the United States of America vas representedby the United vStates Atomic Energy Commission ApplicationV February 11, 1949, Serial No.575,'911

3 Claims.

This inventionrelates to an improved 'method of and apparatus for regulating high voltage. More particularly, this invention relates to a high voltage regulator wherein different parts of the regulating apparatus are maintained at diiierent potentials and wherein a radio-frequency voltage is used. `to couple one part of .the apparatus to the rest ci the associated equipment.

Many typesrof regulator circuits have been developed; however, for certain types of electrical applications it is required `t 'have a high voltage regulator which is stable over a vlarge range -of operating conditions. To achieve this condition, the present invention employs radio-frequency coupling in novel and improved combinationA with Van amplifier to control the operation lof a regulator tube in opposition to fluctuations -within the load circuit. -It is therefore an object of this invention to provide an improved method and apparatus for regulating the high voltageoutnut -of a rectier. 'Another Yobject of the invention is to provide -a high voltage `regulator having stable operation over a large range of load conditions.

Afurther object of `this invention is to provide a radio-frequency circuit coupled to an ampli- AnerA adapted lto control the operation Aof a regulator tube circuit in a. predetermined manner.

A still further object of this invention vis to provide a voltage regulator circuit having a series-connected losser tube coupled by radiofrequency voltages to a controlling amplifier.

A still further Objectis to provide a high voltage regulator of thera dio-frequency type Vwherein the modulation of the radio-frequencyvoltage is accomplished at a high level. Other and further obiects oi this invention will be apparent to those skilled in the art to which it pertains, upon consideration of the following specfcation and drawings, in which:

Figure 1 -shows vvan over-all diagram of a high voltage regulator of thek radio-'frequency coupled type;

' Fig. 2 is -a schematic wiring Adiagram ofthe control circuit and 'voltage standard;

Fig. 3 is a 'schematic wiring diagram of the high voltage regulator control panel; and Fig. 4 is a schematic wiring diagram of the radio-.frecuencvrectifier unit.

Referring to Fig. 1 in detail, a block diagram Aof a high-voltage regulator of the radio-fre- *quen'cy coupled Vtype is lshown. A high voltage rectifier and iilter II of a conventional tvoe has a positive terminal I2 connected to ground f3 by a conductor I4. YAllega-tive terminal f5 ofthe high voltagezsupply Ill is connected to-thecathode of Ya triode tube .Il (connected as -a Aseries losser tube) .by aiconductor I6. The anode of the triode I'I is connected to a resistance-capacitance filter comprising two resistors I8 and I9 and a condenser 2.I; :one side Nof the condenser .2VI `is connected to ground I3. The resistor I9 of the resistance-capacitance lter unit has its remainingend rconnected to :theoutput terminal 22 from which kthe-regulated high voltage is obtainable.

A conductor 23 is connected between the output terminal `22 and azterminal .24 of a high-voltage divider network v26. This network-26 com- .prises the series-connected resistors 21 *and` 28 4with a condenser 29 connected 4in. shunt with the resistor 2l to compensate the network for the higher frequencies. TWO condensers 31 and ..32 by-pass the conductors 33 and e311 to ground I3. These conductors 33 and 34 `couple the voltage dividing network ,26 to a control 'amplifier '36. rEhe high voltage divider housing 3l is connected to ground kI3. The Aconductors 3,3 and 34 terminate in a V.connector 38 which plugs into a receptacle 39 on thecontrol-amplier 36 the `chassis of which is grounded by a -conductorAL This control amplifier 36 will be described in detail later.

'Two terminals 42 and'43 are connected to a suitable source :of alternating current for supplying the controlpa-'mpliiier 3B through a Apair 'of conductors 44 /and 46 and plug and receptacle'l and for supplying -power to the ycontrol box 4.8 through terminals 6 a-nd 'I of terminal strip 4-9. A control cable 5I connects a control box .4,8zto the control ampliier .36 vthrough vplug .52 'and 'a receptacle 53. `Acoaxialcable 54 conveys .the radio-frequency voltage from .the control amplier 36 to a `rectifier `unit 55. The variable rectied raflio-freouencv voltage obtainable .at a terminal 5B of theirectier 55 is .applied to Ythe :control grid -of `the' losser tube `ITI through a codu'ctor 51, while a chassis terminal `58 of the rectifier unit 55 .is .carried to they cathode 'of `the losser tube LIv'I-ibyra. conductor .59.

ReferringLnow to' Fig'..2, thereis showna schematic wiring diagram of the control .amplier 3.6

of the high :voltage regulator-system depicted in Fig. 1.. Thecontroliamplier unit 36 containsas a source Iof radio-irequencyvoltage, a self-'texcited oscillator vwhich comprises a .pento'de vacuum tube .63 and a shielded tunedcircuit 64 connected .between the control grid. fand kthe screen -grid .el'en'fients vof `.this tube. The 'tuned circuit64 includes an inductance 66 and: twocondensefrsv 6l :andi-68 both Jof which far-e connected 23,546,166 i jf.;

3 in shunt across the inductance 69. One end of the inductance 96 is connected directly to the screen grid of the vacuum tube |53 and the other end is connected through a blocking condenser 69 to the control grid of the vacuum tube 33. A resistor 1| is connected between the control grid of the tube 63 and a ground bus 12. A variable tap on the inductance |55 is connected through ar l resistor 13 to a source of regulated positive voltage obtainable at a terminal 14 of a regulated low voltage supply 16. A by-pass condenser 11 is used to provide a low impedance path to ground for any radio-frequency Voltage appearing at the tap on the inductance 66. The cathode, the inner shield, and the suppressor grid of vacuum tube 53 are connected directly to the ground bus Y 12. The anode of the pent-ode tube 63 is connected through a radio-frequency choke coil 13 to a second terminal i9 of the source of regulated positive voltage 16. A radio-frequency by-pass condenser 3| is connected between ground and the cold end of the radio-frequency choke coil 18.

The radio-frequency voltage appearing on the anode of the pentode tube 63 is coupled by a condenser 82 to one side of a shielded tuned circuit 33 of a buier amplifier 84. The tuned circuit 83 consists of a variable condenser 86 and a tapped inductance 81 connected in shunt. The aforementioned tap of the inductance 81 connects through a parasitic suppression resistor 38 to the control grid of a buffer amplier tube 89. .The anode of this tube 89 is connected through another parasitic suppression resistor 9| to the center conductor of a coaxial cable 54, which couples the control amplifier unit 39 to the rectier unit 55 (to be described later). The other side of the tuned circuit 93 is connected to the cathode of the buffer amplifier tube 69 through "a resistor 92 and a condenser 93 connected in shunt. This cathode is also connected to the ground bus 12 by a by-pass condenser 94. The fouter conductor of the coaxial cable 54 is connected by a conductor 93 to a terminal on a current meter 91, and the remaining Vterminal of the current meter 91 is connected to a terminal 4 of 'the receptacle 53. A condenser 98 is connected Abetween the terminals 4 and 5 of the receptacle y53; vterminal 5 is further connected to a terminal 4-99 of an unregulated source of positive voltage |I. A condenser |92 and a resistor |03 are connected to the same terminal of the current meter 'as is the conductor 96. The remaining terminal of the condenser |02 and the resistor |03 areJ con- Ynected together and are further connected to a condenser |04 which is shunted by a resistor |35. vlThe junction between the condensers |02 and |94 -and the resistors |03 and |95 is connected Athrough. a parasitic suppression resistor |01 to the screen grid of the vacuum tube 39. The refmaining'terminal of the condenser |04 and the v'resistor |95 are connected directly to the cathode of the tubei89 which is connected through a --parasitic suppression resistor |08 to the anode vof a vacuum tube |99. The cathode of this vacM -uum tube |99 is connected to the ground bus 12 `by a conductor A tapped bleeder resistor I I2 is connected between the unregulated voltage fterminal 99 and the ground bus 12;V the tap on this resistor I l2 is connected through a parasitic suppression resistor I |3 to the screen grid of the :vacuum tube |09. -The junction between the tap -on the resistor ||2 and the resistor ||3 is bypassed to the cathode of vacuum tube |09 by a condenser I |4.

Terminal I of the receptacle 39, which is connected externally through the plug 38 to the conductor 33, is connected internally through a shunt-connected resistor ||6 and condenser I|1, and further through a second resistor ||8 to the control grid of an input pentode tube |I9. The suppressor grid and the inner shield of the pentode tube I I9 are connected directly to the cathode which is connected through a resistor |2| to the ground bus 12. The screen grid of this pentode tube I I9 receives its Voltage through a parasitic suppression resistor |22 from a third terminal |23 of the source of regulated positive voltage 16. The terminal |23 is bil-passed to ground by a condenser |24. The junction between the cathode of the buffer amplifier tube 89 and the parasitic suppression resistor |98 is connected through a negative feedback loop comprising a condenser |20 and a resistor |21 connected in series to the cathode of the input pentode tube H9. The anode of the input pentode tube ||9 receives its positive voltage, through an anode load resistor |23 and an anode current meter |29 connected in series, from the terminal 14 of the regulated voltage source 15. The anode of the input pentode tube ||9 is also connected through two series-connected glow lamps |30 and |3|, through a current-limiting resistor |32, and then through a parasitic suppression resistor |33 to the control grid of the vacuum tube |09. The anode of the input pentode tube ||9 is also connected through a condenser |34 to the junction between two resistors |32 and |33. The junction between the resistor |32 and the glow lamp |3| is connected through a resistor |33 to a terminal |31 of a source of unregulated negative Voltage |38.

Terminal 2 of the receptacle 39, which is connected externally to the conductor 34, is connected internally through a conductor |39 to the terminal number 3 of the receptacle 53; terminal 2 of the receptacle 39 is also by-passed to the ground bus 'I2 by a condenser |4|. The ground bus 12 is connected to a terminal 4 of the receptacle 39 and aso to the chassis, to which the ground terminal 49 is also connected. Terminal I of the receptacle 53 is likewise connected to ground bus 12. Terminal 2 of the receptacle 53 is connected through a conductor |42 to the terminal 14r of the regulated positive voltage source'16.

The unregulated positive voltage supply IDI is a conventional, full-wave rectifier unit, and comprises a transformer |43, a rectifier tube |44, and a two-section low pass lter composed of two iron core inductances |43` and |41 and two condensers |48-and |49. The output of `this voltage supply is obtainable across the bleeder resistor ||2. f v

The regulated positive Voltage supply 10 is also -a conventional, full-wave type-of rectifier cornprising a transformer |5I, a full-Wave rectifier tube |52, and a pisection low-pass filter comprising an iron-core-inductance|53 and two con- 'winding of the transformer |5|.

the outputof the regulated'low voltage supply16 and apply a predetermined voltage to the Acontrol' connected potentiometer |68 and resistor |69 are f connected between the screen grid of the pentode tube |59 and ther ground bus .12. The swinger on the potentiometer |68 is connectedthrough a resistor |1| to theunregulated positive terminal |51. The anode of the series losser tube is connected to its screen grid by a. parasitic suppression resistor |12 and also .to its control grid by another resistor |13. The .series-connected gaseous regulator tubes |14 and |15 are connected between the cathode of Vthepentode tube |59 andthe ground bus 12 and form a primary voltage standardv for the regulated voltage supply 16. Connected in shunt with these tubes is .a by-pass condenser |11. Another by-pass condenser |18 is connected between the control grid and the cathode of pentode |59.

The positive voltages obtainable `at the .terminals 19 and |23 are regulated by va pair of gaseous regulator tubes |19 and |80 connectedin series; the current through these two gaseous tubes is limited 'by a resistor |82, which .is Vconnected between the unregulated positive voltage terminal |51 and the anode of the gaseousregulator tube |19.

A filter condenser |83 is connected across the output of the regulated positive voltage suppy 16; that is, from terminal 14 tothe ground Vbus 12. The primaries of transformers |43 and |5| are connected to the terminals l and 2 of the plug 41; one line has a'fuse |84 and an fon-off switch |86 inserted between the terminal ofthe plug 41 .and the transformers i43 and |5l. A condenser |81 is connected in shunt across the primary windings of the transformers |43 and |5|, while a second condenser |88 is connected between the ground bus 12 Vand the terminal 2A of the plug 41.

'The supply of unregulated negative `voltage |38 (obtainable at the terminal |31) is provided .by connecting the :cathode of a diode tube |89 to thev Vjunction between one anode of the full-wave rectiertube |52 and one side of the high voltage The anode .of a diode tube |89 is connected to one vend of `a resistor |9l; the other end of `the resistor |9| is connected to the terminal |31. A resistor |92 and a condenser |93 are .connected in shunt between the terminal |31 and the ground bus 12.

The control box 48 for the high Voitage regulator is shown in Fig. 3. Terminal of the terminal strip 49, which is connected externally to the ground bus 12 through terminal of the receptacle 53 of the control amplifier 36 (Fig. 2),

is connected by a lead |94 to one end of three Ation is further connected bya conductor |99 to the terminal 2 of the terminal strip 49.

This terminal 2 is connected externally to the terminal 2 of the receptacle 53 and to terminal 14 of the regulated Vlowcvoltagc supply 16 (Fig.y .2); The "swinger of .the potentiometer |93 `is kconnected by a conductor 20| to the conductor |94. The shafts of the potentiometers 93 and .|91 are ganged .together so that they operate as -a unit. Terminal 3 :ofthe terminal strip 49, which is connectedexternally to the conductor 34` through the control amplifier 36 (Fig. 1), is connected internally by a conductor 202 and a condenser 203 to the swinger of the potentiometer 95. Conductor 4202 is also connected to the swinger of another potentiometer 204 and further to the swinger of sectionZBC of la three pole, double throwswitch 286. A current meter 201 .is connected between the terminals 4 and 5 of theA ter'- minal'strip 49 and is connectedexternally to the terminals 4 .and 5 of the receptacle 5.3 on'the control amplifier 36 (Fig. 2) where it is'inserted between thefunregulated voltage terminal '99 and the current meter'91. Terminal 9 of the terminal strip 49 is connected to one end of the primary winding of a step-down transformer 208 by a conductor 209; `the other end of this primary winding is connected to the swinger of section 206B of the switch 206. The on terminal of section 206B of the'switch 206 .is connected by a conductor 2|| to terminal'1 ofthe terminal strip 49. These terminals 6 and'1 of the terminal strip 49 are further connected by the conductors 44 and 46 to the terminals 42 and 43 (Fig. l). The off vterminal of the switch section 206C, one side of the secondary winding of transformer 298, one side of the potentiometer 204, and the swinger of the potentiometer |96 are all 4connected together by a conductor 2|2. The other side of the secondary winding of the transformer 208 is connected to the swinger of switch section 206A; while the on terminal of this switch section 206A is connected by a conductor 2|3 to the other end ofthe potentiometer 204.

Now referring to the rectifier Vunit as shown in Fig. 4, the center .conductor of the coaxial cable 54 is connected to one end of the primary winding of a radio-frequency transformer 2|4; the other end of the'primary winding iscon- 'nected to the outer conductor vof the vcoaxial cable 54. A Variable condenser 2i6 is connected in shunt Awith the'primary winding for tuning purposes. The coaxial cable '54, which is insulated from the chassis of the rectifier unit 55 by a sleeve 2|1, goes to the control amplifier unit 36 (Fig. 2); here also a similarsleeve 2|1 is used to insulate the cable from the chassis.

One side of the secondary coil `of the radiofrequency transformer 2|4 is connected to `one side of a condenser 2 i8, one end of a resistor 2|9, the anode of a diode tube 22|, and to a terminal 56 on an insulated bushing 223 by a conductor 224. A variable condenser 226 is connected in `shunt across the secondary coil ofthe transformer 2 4 for tuning purposes.

odes of these two diode tubes 22| and 229 Yare connected together by a conductor 23| and are in turn connected to a chassis ground 232 by a Y conductor 233; a terminal 58 is also connected -to this chassis ground v232. The cathodes f these diodes 22! and 229 are connected by a conductor 236 to the junction between the current meter 225 and the condenser Zia.

The operation of this radio-frequency coupled, high-voltage regulator will now be described in detail. The radio-frequency voltage is supplied from the self-excited oscillator 55, which operates in the medium frequency range and the exact frequency of which is determined by the resonant frequency of the tuned circuit 64 connected to the vacuum tube 63. A typical operating frequency might be one in which the inductance BS and the condensers 6l and es resonate at approximately 5 megacycles. The oscillator control .grid'bias is determined by the grid resistorv Hv through which the oscillator control grid current flows; .While the oscillator control grid excitationvoltage is determined by the position of the cathode tap on the inductance 5t.

The Yplate circuit of Vthel oscillator tube 53 is tuned to the fundamental frequency, as determinedby the tuned circuit 54, by the tuned cir-- cuit 83 comprising the inductance Bl and the condenser 3d. This tuned circuit is designed so as to reiiect the proper plate load back to the plate of the oscillator tube 63. The oscillator is shunt fed, in that it receives its plate voltage through the radio-frequency choke coil 78, and the radio-frequency voltage is applied to the tuned circuit through the coupling condenser E2,

thus isolating the tuned circuit 83 from the drect current anode voltage.

The vacuum tube SQ serves as a radio-frequency buiier ampliiier of the class C type. An

amplifier of the class C type is used so as to provide, as nearly as possible, a linear change in output with respect to a change in the modulation volage. Since the buffer amplifier tube .89 is operated with positive grid current, the

grid resistor Q2, and the condenser 93 provide a source of direct current grid bias voltage. The tap on the inductance Si is adjusted to give the proper amount of grid drive to the control grid `of the buffer amplifier tube 09, when the proper plate load is connected in its plate circuit.

The buffer amplier tube 89 is operated oli` or" groundA by the amount of voltage developed across the 'modulator tube H09; and hence the 4cathode of the buier amplifier tube 89 is returned to ground, for radio-frequency voltage, by the a by-pass condenser dei. The resistors H33 and |05 and the condensers iil and ili form a compensated voltage divider for supplying screen grid voltage to the 'buffer tube 89. This network .allows modulation of both the plate and the screen grid of the buier amplifier 84.

Since this regulating system is concerned with changes in the high voltage which may occur at frequencies approaching Zero cycles up to approximately 400 cycles per second (the major variations being due to the 360 cycle ripple component of the high voltage rectier unit i! (Fig.

1), and the remaining variations due to lower `frequency ripple components because of rectifier rjunbalance, line voltage changes, and load changes) a `direct coupled two-stage ampliiier composed of the vacuum tubes l I9 and 109 and their associated components is provided on this chassis to furnish the major portion of the gain of the system.

To protect the vacuum tube lis during the instances when there is no output from the high voltage rectifier unit i l (Fig. l.) or when the output of the regulator is short circuited and a high positivcvoltage is applied to the input terminal 8. l of the receptacle 39, the resistor H6 is used to limit the control grid current owing in the control grid circuit. The condenser II'I which shunts the grid limiting resistor H6 reduces the impedance across this resistor il@ at signal frequencies. The time constant, or the product of the capacitance of the condenser H1 in farads times the resistance of the resistor HB in ohms, must be shorter than that of any other resistance-capacitance combination in the high voltage divider in order that the grid of the input tube H9 shall have applied to it the true volt.- age output of the voltage divider as the high voltage approaches itsI working Value.

The plate ,of the input tube H9 is coupled'to the control grid of the second amplifier or modul lator tube `i519 through two glow lamps 13E. and i3i, which provide a substantially constant di; rect current potential drop and hence place the proper negative voltage on the control, grid of vacuum tube ills. This glow lamp network allows the very slovv direct current variationsto be passed on to the control grid oi vacuum tube .$09. The resistor i3? in the control grid cir,- cuit limits the grid current of the vacuum tube under certain operating conditions, whilethe condenser !34 reduces the impedance'across the network comprising the glow lamps i3@ and |31 and the resistor 32 at the higher signal irequencies. The time constant of the condenser |34, resistor 32 combination is made comparable to that of the condenser lil, resistor H6 combination for the same reasons as set forth previously.

The buffer amplifier tube S9 and the modulator tube iig are connected in series across the output of the power supply itl. The buffer amplifier tube 89, operating as a class C ampliner, offers a substantially constant impedance, while the impedance of the modulator tube |09 varies according to the signal Voltage present at its control grid. Thus, modulation of the radio-frequency voltage is obtained by varying the current which may flow through the modulator tube i053. The current meter 91 indicates this current flow and is used to givea visual check on the performance. The current meter 2N in the control box (Fig. 3) provides a visual indication at the operating position of the cui-- rent iiowing in the modulator-amplier circuit.

.The regulated positive voltage obtainable at the terminall 'ifi is used as a voltage standard for regulating the high voltage output or the high voltage regulator. This standard Voltage is held substantially constant by the direct current amplier tube |59, the low voltage standard comprising the gaseous regulator tubes Iifi and V15, the series losser tube it, and the associated components. The standard voltage obtainable from the terminal lli, which is in the order of 500 volts, is maintained constant within one part in 5000 or better for periods of less than one hour. For longer periods the stabilization is one part in 2500 or better.

The modulated radio-frequency voltage obtainable at the anode of the buffer amplier tube 89 is carried to the rectiier chassis (Fig. 4) by the coaxial cable 5t. The actual coupling between the control amplifier chassis 35 and the rectiiier unit 55 takes place in the radio-frequency coupling transformer 2id. This transformer has a tuned primary and a tuned secondary, and the spacing between the two coils is such asto have a coupling coeicient greater than the critical `value. This coil assembly is immersed intransl'ap-s ruin the vacuum tube.

Referring now to Fig. 3, the. output of' the 'Iforinerloil to provide. the necessary insulation to withstand at least 4G kilovolts direct current with areasonable safetyl factor;

lThe radio-frequency voltage developed across Vthe secondary of the radio-frequency transformer 2|4 is` rectified by a diode 229, and then the pulsating direct current is ltered by the condenser 2|8 plus the input capacity of the series regulator tube or" tubes (Fig. l). The load resistor 2I9 is chosen to atten properly the response curve of the coupling unit 55, and the current meter 2.25 indicates, the amount of direct current voltage output to the control grid of the series regulator tube The diode 22| is a-protective device connected from the -regulator tube |l control grid to cathode to. prevent the control. grid of the losser tube |'i from going positive with respect'tol the cathode and thereby causingan excessive grid 'current to ow and pervoltage standard 16 obtainable at the terminal 14 (Fig. 2) is applied across the resistors |83, |95, and |91 in series to ground. The bottom end of the resistor 28 of the high voltage divider network 26 (Fig. l) is connected through the control amplier 3E to the terminal 3 of terminal strip 49 and then by a conductor 202, switch section 266C, and a conductor 2|2 to the movable contact of resistor |96. Thus it is seen that a Sample of the high negative voltage is compared to a part of the positive standard voltage, the value of which is determined by the settings of the movable contacts of the resistors |93, |96, and |91.

These two voltages, being of opposite sign, add

algebraically to provide the proper low negative voltage to be applied to the control grid of the input tube ||9 of the control amplifier (Fig. 2). The variations in value of the high negative voltage also appear on this low negative voltage which is used to control the regulator system. These variations are amplified by the vacuum tube H9, further ampliied by the modulator tube |09, and are then used to modulate the radio-frequency voltage applied to the control grid of the buffer amplifier tube 89 by the self-excited oscillator tube 63. This radio-frequency voltage, which is varying in amplitude, is coupled by the radio-frequency transformer 2M to the rectier unit 55; here the modulated radiofrequency voltage is demodulated or converted into a varying direct current voltage of such polarity that when it is applied to the control grid of the losser tube the original voltage variations are corrected. Thus when the high voltage tends to change in magnitude, a correcting voltage is applied to the control grid of the series losser tube, which corrects the original variation; and the high voltage is kept substantially constant. The resistors |93 and |97 act as the high voltage une control, while the resistor |96 is the high voltage coarse control.

When the switch 28B is thrown to the on position, three operations are accomplished: the transformer 208 is energized, the resistance element of the potentiometer 204 is connected across the transformer secondary, and a portion of the resistor 204 is shunted across the condenser 263.

In this manner a small alternating current voltage is inserted in series with the high negative voltage sample and modulates the signal voltage applied to the control amplifier input. This in turn modulates the high negative voltage output obtainable at the terminal 22 (Fig. l). This modulation of the high voltage is desirable when a CII :beam scanner is'used tbv-*monitor the beam,v asY for instance when this high voltage regulator is used in conjunction with a mass separator.

Although I have described my invention with respect to a particular embodiment thereof, it is not limited to this embodiment nor otherwise except by the terms of the following claims.

What is claimed is:

1'. In a high-voltageV regulating network of the radio-frequency coupled type wherein part of the apparatus is maintained at a lowK potential, the combination comprising a losser tube connected in series with a load across a source of voltage to beregulated, a resistor bank across said load for'obtaining a sample ofA the voltage thereacross, a standard voltage source, a comparison circuit `comparing' theoutput of.' said standard voltage source with the voltage across said resistor bank for producing a differential voltage, a source of radio-frequency voltage, a buffer amplifier: having a control electrode. connected to, said radiofrequency voltage source; and thereby amplifying said radio-frequency voltage, a modulator tube having a control electrode and having an output connected to said buifer amplifier and modulating the amplified radio-frequency output thereof, a direct coupled amplier having its output applied to the control electrode of said modulator, said direct coupled amplifier having control means, and means impressing upon said control means the differential voltage from said comparison circuit, whereby said differential voltage is amplied and impressed on said radiofrequency voltage by said modulator, and a rectifier unit connected between said buifer amplier and the grid of said losser tube for demodulating said modulated radio-frequency voltage and applying the resulting varying unidirectional voltage to the control grid of said losser tube for controlling the internal impedance thereof, and counteracting variations in said load voltage.

2. In a high-voltage regulating network of the radio-frequency coupled type wherein part of the apparatus is maintained at a low potential, the combination comprising a losser tube connected in series with a load across a source of Voltage to be regulated, a resistor bank across said load for obtaining a sample of the voltage thereacross, a comparison network connected to said resistor bank and including a standard voltage source and producing a differential voltage from a comparison of the resistor bank voltage and the standard voltage, a source of radio-frequency voltage, a buifer ampliner vacuum tube and a modulator vacuum tube each having at least a cathode, an anode and a control grid, said buffer amplifier tube and said modulator tube being connected in series across a source of power and said radio-frequency voltage source being connected to the control grid of said buffer amplifier, a direct coupled amplifier coupled to the control grid of said modulator tube, said direct coupled amplifier having a control grid connected to the Output of said comparison network whereby a differential voltage produced by the comparison of said sample voltage and said standard voltage is amplified and applied to the control grid of the modulator tube for varying the anode current of said modulator tube, thereby varying in amplitude the radio-frequency output voltage of said buffer amplifier tube, and a rectifier unit having an input circuit connected to the anode of said bui-ier amplifier for demodulating said variableamplitude radio-frequency voltage, and an output circuit applying said varying unidirectonal voltage to the control grid of said losser v voltage.

3. In a voltage regulator the combination comprising a variable electronic impedance connected between a voltage source and a load, a voltage divider connected across said load, a comparison network including a standard voltage source and means to compare the voltage across a predetermined portion of said voltage divider to said standard voltage whereby a dierential voltage is produced, an amplier tube having an anode and control electrode, means impressing said differential voltage upon the control electrode of said amplifier tube, a modulator tube having an anode and control electrode, means connecting the anode of said amplier to the control electrode of said modulator tube, a cathode-modulated class C amplifier tube having an anode, cathode, and control electrode, means connecting the cathode of said modulated amplier 12 to the anode of said modulator tube, a power supply connected in series with said'modulator and modulated amplifier, a self-excited oscillator coupled to the control electrode of said modulated amplier, a rectifier circuit changing the output of said modulated amplifier to a direct current voltage, and means impressing said direct current voltage upon said variable electronic impedance whereby the value of said impedance is varied to compensate for fluctuations in loa-d voltage.

KENNETH G. MORRISON.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2@ 2,147,446 Koch Feb. 14, 1939 2,386,548 Fogel Oct. 9, 1945 

